Greek archaeologists excavating a massive Alexander the Great-era burial mound complex at Kasta Hill, in the northern Greek region of Serres, have found the skeleton of a man in a limestone grave buried in the floor of the third chamber.

Within the grave is a wooden coffin that was once held together by iron and bronze nails, and studded in bone and glass decorations.

Pluto, the god of the underworld (previously known as Hades) wears a laurel wreath on his head, commanding a chariot drawn by horses into the underworldGreek Ministry of Culture

The archaeologists say that the coffin had disintegrated over time and the skeletal remains were found both inside and outside the grave in the floor, probably the result of looting of the site in ancient times.

The outside dimensions of the grave measure 3.23m long by 1.56m wide and 1m deep. By calculating the supports used to hold up the coffin, the archaeologists estimate that the person buried in the grave was at least 1.8m tall.

The excavated limestone grave set into the floor of the third chamber once held a wooden coffin decorated with bone and glassGreek Ministry of Culture

Artist\'s illustration of the limestone grave found beneath the floor in the third chamberGreek Ministry of Culture

The Greek Ministry of Culture said in a statement: "It is probably the monument of a dead person who became a hero, meaning a mortal who was worshipped by society at that time. The deceased was a prominent person, since only this could explain the construction of this unique burial complex."

The skeletal remains will now be analysed by experts and the Greek government plans to share results of this analysis on 29 November.

The first official video to be released of the tomb, which shows archaeologists excavating the chambers, removing the sandy soil and uncovering the mosaic floor.

Other guesses included Alexander the Great's mother Olympias, or his wifeRoxana. But given that the body is likely to be male, current bets are on the generalLaomedon, who was a friend of Alexander's.

Largest amount of marble ever found

The Lion of Amphipolis, found in 1912 in the riverbed of the Strymónas River, once stood at the top of the burial mound found on Kasta Hill(Vlahos Vaggelis/Wikimedia Commons)

The archaeologists say that the amount of marble used to build this tomb is the biggest ever seen in Macedonia, and they have so far found at least 500 marble pieces in the area surrounding Kasta Hill, including at least 100 different types of architecture, including features like pillars and cornices.

The famous Lion of Amphipolis, one of the best preserved monuments from 4th century BC, was found in 1912 by the Greek army in the river bed of the Strymónas.

Acclaimed architect Michael Lefantzis believes it once stood at the highest and most central point of the Kasta Hill mound. It now stands next to the old bridge over Strymónas River, on the street Amphipolis-Serraiki Akti.

Slabs of marble from the Kasta Hill tomb have been found in the artificial reservoir of Lake Kerkini, which flows into the Strymónas River(Greek Ministry of Culture)

Lake Kerkini is the site of an artificial reservoir created in 1932 from an area of extremely extensive marshland.

Its primary inflows and outflows come from the Strymónas River, and the archaeologists revealed that in the lake, they discovered within the sediment, alternating layers of sand and marble.

When compared to samples of the marble on the inside and outside of the tomb, the archaeologists say that the marble discovered in the lake is a match.

The tomb discoveries so far

In the last three months, news of discoveries from the tomb have been coming at great frequency, sometimes once a week.

Caryatids have been discovered at the ancient Amphipolis tomb in GreeceGreek Ministry of Culture

The caryatid statues being excavated from sandy soil in the Amphipolis tombGreek Ministry of Culture

Seven-foot-tall caryatid Greek statues have been uncovered in the Amphipolis tomb on Kasta HillGreek Ministry of Culture

The statues stand over 7.5ft tall and amazingly their bodies and delicately carved feet are still intact, with them wearing kothornoi, ancient Greek ladies' shoes that resemble platform sandals.

The multitude of layers and folds that make up the caryatids' clothing feature very intricate details with a visible under-layer and traces of red and yellow paint still remaining on their feet.

The completely excavated mosaic floor of Persephone being abducted by Pluto and taken to the underworldGreek Ministry of Culture

The marble threshold to the third chamber has now been uncoveredGreek Ministry of Culture

In October, the archaeologists discovered a stunning mosaic floor in the third chamber that tells the mythical tale of Zeus' daughter Persephone being abducted by Pluto, the god of the underworld (who used to be known as Hades).

It was customary in these traditional representations of the tale for Hermes, who among other things was a guide to the underworld to be present in the depictions.

According to the Greek Ministry of Culture, this mosaic bears a striking resemblance to the "Rape of Persephone" wall mural in Tomb I, the supposed Macedonian Tomb of Persephone at the royal cemetery in Vergina (Aigai). This is the first time that a mosaic made from pebbles has been found in a funerary monument.